WE have demonstrated, in the first article, that the earth, in consequence of the mutual attraction between the particles of matter, and of the centrifugal force which results from its diurnal revolution, behoved [sic] to assume the figure of a spheroid, the two diameters of which differ about a 230^th part; and that nothing but the changes made on its surface by the motions of the air and of the waters, could augment this difference, in the manner alledged by those who measured by a degree under the equator, and another within the polar circle.  This figure of the earth, which agrees so well with the laws of hydrostatics and with our theory, indi- [157] cates that, at the time it assumed its figure, it was in a state of fluidity.  We have also proved, that the projectile motion, and the motion of rotation, were impressed at the same time, and by the same impulse. It will the more readily be admitted, that the earth was originally in a state of liquefaction, when it is considered, that the greatest part of the materials of which this globe is composed, are either vitrification, or vitrifiable by fire.  The impossibility of rendering the earth fluid by the operation of waters confirms this hypothesis; because there is infinitely more earth than water; and the water is not able to dissolve sand, rocks, and hard minerals.

It is, therefore, evident, that the earth assumed its figure when in a melted state:  And, to pursue our theory, it is natural to think, that the earth, when it issued from the sun, had no other form but that of a torrent of melted and inflamed matter; that this torrent, by the mutual attraction of its parts, took on a globular figure, which its diurnal motion changed into a spheroid; that, when the earth cooled, the vapours, which are expanded like the tail of a comet, gradually condensed, fell down in the form of water upon the surface, depositing, at the same time, a slimy substance, mixed with sulphur and salts, part of which was carried, by the motion of the waters, into the perpendicular fissures of the strata, and produced metals; and the rest remained on the surface, and gave [158] rise to the vegetable mould which abounds, in different places, with more or less of animal and vegetable particles, the organization of which is not obvious to the senses.

Thus the interior parts of the globe were originally composed of vitrified matter; and, I believe, they continue so at present.  Above this vitrified matter, were placed those bodies which the fire had reduced into the smallest particles, as sands, which are only portions of glass; and, above these, pumice stones, and the scoriae of melted matter, which produced the different clays.  The whole was covered with water to the depth of 5 or 600 feet,* which originated from the condensation of the vapours, when the earth began to cool.  This water deposited a stratum of mud, mixed with all those matters which are capable of being sublimed or exhaled by fire; and the air was formed of the most subtile vapours, which, from their levity, rose above the water.

Such was the condition of the earth, when the tides, the winds, and the heat of the sun, began to introduce changes on its surface.  The [159] diurnal motion of the earth, and that of the tides, elevated the waters in the equatorial regions, and necessarily transported thither great quantities of slime, clay, and sand, and by thus elevating these parts of the earth, they perhaps sank those under the poles about two leagues, as was formerly remarked:  For the waters would easily reduce into powder pumice-stones, and other spungy [sic] parts of the vitrified matter upon the surface, and, by this means, excavate some places, and elevate others, which, in time, would produce islands and continents, and all those inequalities on the surface, which are more considerable towards the equator than the poles.  The highest mountains lie between the Tropics and the middle of the Temperate Zones, and the lowest from the polar circles towards the poles.  Between the Tropics are the Cordeliers, most of the mountains of Mexico and the Brasils [sic], the great and lesser Atlas, the mountains of the Moon, &c.  Besides, both the land and the sea have most inequalities between the tropics, as is evident from the incredible number of islands peculiar to those regions.

However independent this hypothesis, concerning the original state of the globe, may be of my general theory, I have chosen to refer to it in this article, to show the connection and possibility of the system endeavoured to be established in the first article.  It may only be remarked, that my theory is not opposed by the [160] facts; that I take the earth nearly as it stands at present; and that I lay hold of none of those suppositions which are often used in reasoning concerning the former condition of this globe.  But, as I here offer a new idea upon this subject of the sediment deposited by the waters, which, in my opinion, gave rise to the upper stratum of the earth, it will not be improper to exhibit the reasons upon which it is founded.

The vapours exhaled from the earth produce rain, dews, thunder, lightening [sic], and other meteors.  These vapours, therefore, are mixed with particles of water, air, sulphur, earth, &c.; and it is the solid earthly particles which constitute the slime or mud under consideration.  The purest rain-water deposites [sic] a quantity of this mud; and, when a quantity of dew is collected, and allowed to corrupt, it produces a greater proportional quantity of mud, which is fat, unctuous, and of a reddish colour.

The upper stratum of the earth is composed of this mud, mixed with particles of animal and vegetable substances, or rather with particles of stone and sand.  It may be remarked, that most arable land is reddish, and more or less blended with heterogeneous matters.  The particles of stone or of sand found in it are of two kinds; the one is gross and heavy, the other fine, and sometimes impalpable.  The gross is detached from the inferior stratum by labouring the ground; or rather, the upper stratum, by pene- [161] trating the inferior, which is composed of sand or gravel, forms what is called fat, or fertile sand.  The finer species proceeds from the air, falls down with the dew or rain, and intimately incorporates with the vegetable mould, or upper stratum.  This last is nothing more than the dust, transported by the air, and again deposited during a moist atmosphere.  When the quantity of this mud is great, in proportion to the partaicles of stone or sand, the soil is red and fertile; if it be considerably mixed with animal and vegetable substances, it is blackish; but, if the quantity of mud, and of vegetable and animal substances be small, the soil is white and barren; and, even when the partaicles of sand, stone, or chalk, which compose these barren soils, are mixed with a considerable quantity of animal and vegetable substances, they become black and light, but have very little fertility.  According, therefore, to the different proportions of these three ingredients, soils are more or less fertile, and differently coloured.

In order to acquire distinct ideas concerning the strata of the earth, we shall take for an example the pits at Marly-la-Ville, which are exceedingly deep.  It is situated in a high, but flat and fertile country, and its strata lie horizontally.  I procured specimens of all these strata in their order from M. Dalibard, an eminent botanist, and a man of science; and, after having proved the matters they respectively consist [162] of with aqua fortis, I arranged them in the following table.

Table of the different beds of earth at Marly-la-Ville, to the depth of 100 feet.

	Feet. Inch.
A free reddish earth, mixed with a large quantity of mud, a little vitrifiable sand, and a greater proportion of calcinable sand, or gravel	13
A free earth mixed with gravel and with more vitrifiable sand	2     6
Mud mixed with a large quantity of vitrifiable sand, which made but a small effervescence with aqua fortis	3
Hard marle, which effervesced violently with aqua fortis	2
A marley stone, very hard	4
Marle in powder, mixed with vitrifiable sand	5
Fine vitrifiable sand	1     6
Marle resembling earth, mixed with a little vitrifiable sand	3     6
Hard marle, in which was found genuine flit	3     6
Gravel, or marle in powder	1
Carried over [163]	39
Brought over	39
Eglantine, a hard ringing stone, of the grain of marble	1     6
Marley gravel	1     6
Marle in the form of hard stone, with a fine grain	1     6
Marle like stone, with a coarser grain	1     6
Marle still more gross	2     6
Fine vitrifiable sand, mixed with fossil sea-shells, which had no cohesion with the sand, and which still preserve their natural colours	1     6
Fine gravel, or marle-dust	2
Marle in the form of a hard stone	3     6
Marle in the form of coarse powder	1     6
Hard stone, calcinable like marble	1
A gray vitrifiable sand, mixed with fossil shells, particularly with oisters and spondyles, which had no cohesion with the sand, and were not petrified	3
A white vitrifiable sand, mixed with the same shells	2
A vitrifiable sand, with red and white streaks, and mixed with the same shells	1
A coarser vitrifiable sand, mixed with the same shells	1
Carried over [164]	64
Carried over	64
A fine gray vitrifiable sand, mixed with the same shells	8     6
A fine unctuous sand, with very few shells	3
Brown free stone	3
Vitrifiable sand, stripped [sic] with red and white	4
A white vitrifiable sand	3     6
A reddish vitrifiable sand	15 _________
Total depth of the pit	101

            I mentioned above, that I had examined all these substances with aqua fortis, because no other test can enable us to make real distinctions between earthy bodies of the same or of different appearances.  Those which effervesce and suddenly dissolve on the application of the aqua fortis, are generally calcinable.  Those, on the other hand, upon which that acid makes no impression, are vitrifiable.

            From the above enumeration of strata it is evident, that the land at Marly-la-ville was formerly covered with the sea, to the depth of 75 feet, since shells are found 75 feet below the surface.  Those shells have been collected and deposited by the water, along with the sand which contains them; and the whole superior strata, excepting the uppermost, have been transported thither by the motion of the waters, and [165] deposited in the form of sediment, as is apparent from their horizontal position, from the mixture of sand, shells, and marle, which last is composed of decayed shells; and even the upper stratum has been almost wholly formed of slime or mud, with a small mixture of marle.

            I have chosen this example, because it is least favourable to my theory; for it appears, at first view, difficult to conceive how the mud deposited by the dew and rains should produce a bed of vegetable soil 13 feet thick.  But it ought to be remarked, that a soil of this thickness is rarely to be found, especially in high countries.  The general run of soils are from three to four feet, and often they exceed not one foot.  The soil is thickest in plains surrounded with hills; because the rains daily bring fresh supplies from the higher grounds.  But, abstracting from this supposition, it is plain, that the upper strata formed by the sea, are thick beds of marle.  It is natural to think, that the upper stratum, above mentioned, was originally much thicker, and that, beside the 13 feet, the sea would leave a considerable quantity of marle.  But this marle, being exposed to the action of the air, or fains, and of the rays of the sun, would soon be reduced into a fine powder.  The sea would not leave this land suddenly, but would continue for some time occasionally to cover it, either by the motion of the tides, or by extraordinary swells during great storms; and, [166] of course, the upper stratum would be mixed with mud, clay, and other slimy bodies.  After being entirely above the reach of the waves, plants would begin to grow, and the soil would constantly accumulate, and be tinged with a reddish colour, by the mud deposited from dews and rain.  Culture would still farther increase both its fertility and its thickness, and, by allowing the dews and rains to penetrate deeper, would in the end produce this soil of 13 feet.

            I shall not here examine, whether the reddish colour of vegetable mould proceeds from a quantity of iron contained in the mud deposited by rain and dews.  This point, which is of some importance, shall be discussed when we come to treat of minerals.  It is sufficient to have given a view of the manner in which the upper stratum has been formed:  We shall now prove, by other example, that the formation of the interior strata of the earth must likewise have originated from the operation of the waters. 

            The upper stratum of the globe, says Woodward, that magazine for the formation and support of animals and vegetables, is mostly composed of vegetable and animal matter, and is in perpetual fluctuation.  All the animals and vegetables which have existed since the creation, have successively extracted from this stratum the materials of which their bodies are constructed; these they again restore at their dissolution, where they remain prepared for the successive forma- [167] tion of new bodies of the same species; the matter which forms one body being naturally disposed to make another of the same kind.*  In uninhabited countries, where the woods are never cut, nor the herbs brouzed [sic] by cattle, the soil is constantly augmenting.  The soil, in all woods, even in those which are occasionally cut, is from 6 to 8 feet thick, and has originated from decayed leaves, and other parts of vegetables.  I have often remarked, upon an old Roman way which runs across Burgundy, that the stones with which it was constructed are covered with a black mould of more than a foot thick, and nourishes trees of a considerable size.  This soil could only be produced by the gradual and successive destruction of vegetable bodies.  As vegetables derive more of their substance from the air and from water, than from the earth, when they decay, they add more to the earth than they extracted from it.  Besides, forests collect and retain vapours and moisture; and, of course, in old woods, the soil is greatly augmented.  But, as animals restore much less to the earth than they take from it; and, as men consume vast quantities of wood and herbs, for feuel [sic] other purposes, it follows, that the vegetable soil of populous countries must continually diminish, and become, in time, like that of Arabia Petrea, and other eastern countries, which were first inhabited, where nothing is to [168] be found but sand and salts; for the fixed salts of plants and of animals remain, while all the other parts volatilize, and are carried off by the air.

            Let us next examine the position and formation of the interior strata.  The earth, says Woodward, wherever it has been dug, is composed of beds or strata, one above another, in the same manner as if they had proceeded from successive sediments deposited by water.  The beds that lie deepest are thicker than those immediately agove them, and they grow gradually thinner till they arrive at the surface.  Seashells, teeth, and bones of fishes, are found in these beds, and not only in those which are soft, as chalk, clay, and marle, but even in beds of hard stone, marble, &c.  These productions of the sea are incorporated with the stone, and, when separated, leave in the stone the figure of their surface delineated.  “I was abundantly assured,” says this author, “that the circumstances of these things in remoter countries were much the same with those of ours here:  That the stone, and other terrestrial matter, in France, Flanders, Holland, Spain, Italy, Germany, Denmark, Norway, and Sweden, was distinguished into strata, or layers, as it is in England:  That those strata were divided by parallel fissures:  That there were inclosed in the stone, and all the other denser kinds of terrestrial matter, great numbers of shells, and [169] other productions of the sea; in the same manner as in that of this island.  To be short, by the same means I got sufficient intelligence that these things were found in like manner in Barbary, In Egypt, in Gujiney, and other parts of Africa:  In Arabia, Syria, Persia Malabar, China, and other Asiatick [sic] provinces:  In Jamaica, Barbadoes, Virginia, New England, Brasil, Peru, and other parts of America.”  P. 6. 41. 42. &c.

            Woodward gives no authority for his assetion, that shells are found in the strata of Peru.  But as, in general, his facts are true, I doubt not but his information has been good; and I am persuaded that shells exist in the strata of Peru, as well as every where else.  I make this remark on account of a doubt which has been entertained on this subject, and which shall afterwards be considered.

            In digging a well at Amsterdam, 232 feet deep, the strata were arranged in the following order:  7 feet of vegetable soil; 9 feet of turf; 9 feet of soft clay; 8 feet of sand; 4 of earth; 10 of clay; 4 of earth; 10 of sand; 2 of clahy; 4 of small white sand; 5 of dry earth; 1 of soft earth; 14 of sand; 8 of clay mixed with sand; 4 of sand mixed with shells; then 102 feet of clay; and, lastly, 31 feet of sand.*

            It is uncommon to dig so deep before we find water:  But this experiment is remarkable in [170] many other respects.  1st, It demonstrates that the sea communicates not with the interior parts of the earth by means of filtration: 2d, That shells are found 100 feet below the surface in a country extremely low; and, consequently, that the land of Holland has been elevated 100 feet by the sediments of the ocean:  3d, It may be concluded, that the bed of clay of 102 feet, and the bed of sand, 31 feet of which only had been dug, and whose actual thickness is unknown, lie near to the antient and original earth, which existed before the motion of the waters began to change its surface.  In the first article, it was remarked, that, in order to discover the antient earth, we must dig in the northern, rather than in the southern regions; and in the low and plain, rather than in the elevated countries.  These circumstances nearly concurred in the present case. We only wish that the pit had been dug deeper, and that the author had informed us, whether shells, or other sea-bodies, were intermixed with the last strata of clay and of sand.  This experiment confirms what was above advanced, that the strata are always thicker in proportion to their depth.

            The earth consists of parallel and horizontal strata, not in the plains only, but, in general, the hills and mountains have the same structure.  The strata of the mountains are even more conspicuous than those of the plains; for the plains are commonly covered with great quantities of [171] sand and earth brought from the higher grounds by the waters; and, therefore, to find the antient strata, we must dig deeper in the plain than in the mountains. 

            I have often remarked that, when the top of a mountain is level, its strata are likewise level; but, when the top is not horizontal, the strata follow the direction of its declivity. It has frequently been alledged, that the beds of quarries incline to the east.  But in all the chain of rocks which I have examined, I found, that these beds always follow the declivity of the hill, whether its direction be east, west, south, or north.  In raising stones from the quarry, they are always separated according to their natural position; and, if cut in a contrary direction, it is impossible to raise them of any considerable size.  In all good masonry, the workmen place the stones in the direction in which they lay in the quarry.  If laid in an opposite position, they will split, and not be able to resist the weight of the incumbent building.  Hence we may conclude, that stones have been originally formed in horizontal beds; that these beds have been successively accumulated above each other, and have been composed of materials, the resistance of which is stronger in that than in any other direction.

            Every stratum, of whatever kind, whether it be horizontal or inclined, is of an equal thickness through its whole extent.  In the quarries round Paris, the stratum of good stone is but a- [172] bout 18 or 20 inches thick throughout.  In the quarries of Burgundy, the stone is much thicker.  The same inequalities take place in marbles.  The white and black marbles are thicker than those that are coloured; and there is a hard stone with which the people of Burgundy cover their houses, that exceeds not an inch in thickness.  Thus, different strata differ much with regard to thickness; but each stratum uniformly preserves the same thickness through its whole extent.  This difference is so great, that strata are to be found, from less than a line, to 1, 10, 20, 30, and 100 feet thick.  Both antient and modern quarries, which are dug horizontally, the shafts of mines, and the working of lead, both longitudinally and transversely, prove that strata extend a great way on all sides.  “It is well known,” as the historian of the academy observes, “that all stones have originally been a soft paste, and that, as stones are almost every where to be met with, the surface of the earth, in all these places, at least to a certain depth, must have consisted of mud and slime.  The shells found in most quarries demonstrate, that this mud was an earth diluted by the water of the sea; and, consequently, that the sea once covered all these places; but the sea could not cover them, without, at the same time, covering all places that were lower, or on the same level.  Now, it is impossible that the sea could cover all those places where there are quarries, with- [173] out covering the whole surface of the globe.  If the mountains were then formed, the sea must also have covered them; for they are full of rocks and quarries, and shells are often found in them.

            “The sea, then,” continues he, “covered the whole earth; and hence all the beds of stone in the plains are horizontal and parallel:  The fishes, therefore, were the most antient inhabitants of the globe; for neither land-animals nor birds could exist.  But how has the sea retired into those vast basons [sic] which it now occupies?  The most natural supposition is, that the earth, at least to a certain depth, was not all equally solid, but interspersed with vast vaults or caverns, the arches of which would remain for a time, and at last suddenly fall in.  The waters would then rush into these hollows, fill them up, and leave a part of the surface dry, which would become a convenient habitation for land-animals and birds.  The shells found in quarries strongly confirm this idea; for nothing but the bony parts of fishes could be preserved so long in the earth.  Besides, shells commonly lie in vast masses in certain parts of the sea, where they remain immoveable, and form a species of rocks or banks; they could not, therefore, follow the sea, which suddenly abandoned them.  For this last reason it is, that we find such numbers of fossil-shells, and so few vestiges of other fishes, which [174] is a farther proof that the waters retired with rapidity into their present basons.  When the vaults sunk down, it is very probable that mountains were elevated by the same cause, and placed upon the surface with rocks and quarries already formed.  But the beds of these quarries could not preserve their original horizontal position, unless they were raised exactly perpendicular to the surface, which would rarely happen.  Thus, as we formerly remarked,* the beds of stone in mountains are all inclined to the horizon, though they be parallel to each other; for they changed not their position with regard to one another, but with regard only to the surface of the earth.”⁺

            These parallel beds of earth or of stone, which have been formed by sediments of the ocean, often extend to considerable distances; we even find, in hills separated by vallies [sic], beds of the same materials upon equal levels. This observation has a perfect correspondence with the equal altitudes of opposite hills.  The truth of this fact may be easily established; for, in all hills separated by narrow vallies [sic], where stone or marble is found on one hill, we uniformly find thse very substances, at the same level, on the opposite hill.  I have traced a quarry of marble 12 leagues in length; its breadth is also considerable, though I have not been able exactly to ascertain it.  I have often observed, that [175] this bed of marble has every where the same thickness; and that, in hills separated by a valley of 100 feet deep, the same bed always appeared at the same altitude.  I am firmly persuaded, that this observation holds with regard to all quarries of stone or of marble that contain shells; but it applies not to beds of free-stone.  We shall afterwards explain why free-stone is not dispersed, like other matters, in horizontal beds, but in blocks, irregular both in form and position.

            In has likewise been remarked, that, on the opposite sides of straits of the sea, the strata are the same.  This observation is important, and may lead to the discovery of those necks of land, or islands, that have been separated from the Continent.  It proves, for example, the England has been separated from France, Spain from Africa, and Sicily from Italy:  And it is to be regretted, that the same observation has not been made upon all straits.  I have no doubt but it will hold universally.  We know not, whether, in the straits of Magellan, the longest we are acquainted with, the same strata are to be found at the same altitude; but we perceive, from very exact charts, that the opposite coasts, which are high, have corresponding angles like those observable in our inland mountains; and this further proves Terra del Fuego to have been formerly a part of the Continent of America.  The same remark has been made with regard to the [176] strait of Forbisher; and the island of Friesland appears to have been separated from the continent of Greenland.

            The Maldiva islands are separated from each other by small branches of the sea; and on each side of the opposite islands, the strata of rocks, &c. are the same.  These islands, which, when taken together, extend about 200 leagues in length, were formerly one.  They are divided into 13 provinces, called Clusters.  Every Cluster contains a great number of small islands, most of which will soon be under water.  It is remarkable, that each of these 13 Clusters is surrounded with a chain of rocks of the same stone, and that there are only three or four small and dangerous openings through which each of them can be approached.  They are all placed in a line, with their ends to each other, and appear evidently to have been once a long mountain crowned with rock.*

            Several authors, as Verstegan, Twine, Sommer, but particularly Campbell, in his description of the county of Kent, give striking proofs that England was formerly joined to France, and that the neck of land which divides them had been carried off by the sea, which retired, and left a great quantity of low marshy ground along the southern coasts of England.  As a farther proof of this fact, Dr Wallis has attempted to show an affinity between the antient language of the [177] Gauls and of the Britains [sic]; and he adds several other remarks which shall be related in the following articles.

            If travellers observed the figure of lands, the position of mountains, and the windings of rivers, they would perceive that opposite hills are not only composed of the same materials, at the same altitude, but that they are also nearly of an equal height.  In all the places where I have travelled, I uniformly remarked this equality in the height of opposite hills, especially when they are separated by valleys not above a fourth or a third of a league wide.  In valleys of greater width, it is difficult to judge of the height or equality of hills; for, on looking over a level and extensive plain, it appears to rise; and distant hills appear to sink.  But this is not the place to account for these phaenomena.  Besides, it is not easy to determine, by the eye, the middle of a large valley, unless there be a river in it.  But, in narrow valleys, the judgment of the eye is more certain.  That part of Burgundy comprehended between Auxerre, Dijon, Antun, and Bar-sur-seine, and of which a considerable portion is called le Bailliage de la Montagne, is one of the most elevated parts of France.  From one side of the these mountains, which are only of the second order, the water runs to the ocean, and, from the other, to the Mediterranean.  There are points of partition, as at Sombernon, Pouilli in Auxois, &c. where [178] the water may be turned at pleasure, either to the ocean or to the Mediterranean.  This high country is intersected with a number of small valleys, and most of them are watered with rivulets.  Here I have a thousand times observed the corresponding angles of the hills, and their equality as to height; and I can with confidence affirm, that the salient or prominent angles are uniformly opposed to the concave ones, and that the heights of the two sides are nearly the same.  The farther we advance in this high country, where the points of partition mentioned above, the mountaints are the higher.  But this height is always the same on the opposite sides of the valleys, and the hills rise or fall equally. The same observation I have repeatedly made in several other provinces of France; but they extend not to very high mountains; for these are more irregular as to height, and often terminate in unequal points or peaks.  In frequently traversing the Alps and Appennines, I observed, that the angles in effect, corresponded; but that it is almost impossible to judge, by the eye, concerning the quality or inequality in the heights of opposite mountains; because their tops are lost in the clouds.

            The different strata composing the earth are not arranged according to their specific gravities. Beds of heavy matter are frequently placed above those of lighter.  Solid rocks are often supported by beds of earth, clay, or sand, which [179] have much less specific gravity. This is the case with most hills, and is easily perceived.  But, in high mountains, the summits are not only rocks, but these rocks are supported by others; and this structure runs through such an extent of country, where one mountain rises out of another, that it is difficult to determine whether they are founded on earth, or of what nature this earth is.  I have seen rocks cut perpendicularly for some hundreds of feet; but these rocks rested upon other rocks, without my being able to perceive where they ended.  May we not, however, be allowed to conclude from the less to the greater?  Since the rocks of small mountains, the bases of which are visible, rest upon earths less heavy and less solid than stone, is it no reasonable to think, that earth is likewise the basis of high mountains?  Besides, all I have here advanced tends to prove, that heavy bodies might be accumulated, by the motion of the waters, above light ones; and, if this really takes place in most hills, it is probable that it has happened in the manner pointed out by my theory.  But, should it be objected, that I had no reason to suppose, that, prior to the formation of mountains, the heavier matter was below the lighter; I answer, that I affirm nothing with regard to this article; because there are many ways by which this effect might be produced, whether the heavy matter was above or below, or placed indiscriminately:  For, in order to [180] conceive how the sea could first form a mountain of clay, and then crown it with rocks, we have only to consider, that the sediments might be transported from different places, and that they might consist of different materials.  The sea might transport from one place several sediments of clay, and afterwards deposite [sic] sediments of stony matter; either because all the clay at the bottom, or on the coasts, was exhausted, and then the waves would attack the rocks; or, rather, because the first sediments were transported from one place, and the last from a different one.  Besides, the latter corresponds exactly with experience; for, it is a known fact, that beds of earth, stone, gravel, sand, &c. follow no rule of arrangement, but are placed indifferently, and, as it were, by chance, one above another.

            This chance, however, ought to have some rules, which can only be discovered by analogy and probable conjecture.  We have seen, that, according to my theory of the formation of the globe, that its interior parts should consist of vitrified matter, similar to vitrified sand, which is only the fragments of glass, and of which the clays are only the scoriae, or decomposed parts.  Agreeable to this supposition, the centre of the earth, and even near to the surface itself, should be composed of glass or vitrified matter, and above this should be found sand, clay, and other scoriae.  Thus the earth, in its original state, [181] was a nucleus of glass, or of vitrified matter, either compact like glass, or divided like sand, (for that circumstance depends on the degree of heat applied); above this matter was sand; and, lastly, clay.  The soil, or external covering, was produced from the air and the mud of water; and it is more or less thick according to the situation of the ground; more or less coloured, according to the different mixtures of mud, sand, clay, and the parts of decayed animals and vegetables; and more or less fertile, according to the abundance or deficiency of these parts.  To show that this account of the formation of sand and clay is not altogether imaginary, I shall add a few remarks.

            I suppose the earth, in its first state, to have been a spheroid of compact glass, covered with a thin crust of pumice-stone, and other scoriae of melted matter.  The agitation of the air and of the water would soon reduce this crust of pumice into powder or sand, which, by uniting into masses, would give rise to free-stone and flints, the varieties of which, with regard to colour and density, depend upon the different degrees of fineness of the sand that composed them.

            The constituent parts of sand unite by the application of fire, become very hard, compact, and more or less transparent according to the purity of the sand:  But, on the other hand, when exposed to the action of the air, it exfo- [182] liates, falls down in the form of earth, and may thus produce clays of different kinds.  This dust, which is sometimes yellow, sometimes brilliant, and is used to dry writings, is nothing else than fine sand, somewhat corrupted, and nearly reduced to an elementary state.  In time, its particles become so attenuated and divided, that they lose the power of reflecting light, and acquire all the properties of clay.  On examining a piece of clay, many of these shining or talky [sic] particles appear, they not having yet entirely lost their original form.  Sand, therefore, in process of time, may produce clay; and this clay, by a farther division, acquires the qualities of a mud or slime, a vitrifiable matter of the same nature with clay.

            This theory is confirmed by daily experience.  In washing sand, the water becomes impregnated with a black, soft, fatty earth, which is a genuine clay.  The mud swept from streets paved with free-stone is black and very fat, and, when dried, it discovers itself to be an earth of the same nature with clay.  Clay, taken from places where there is neither flint nor free-stone, and diluted with water, always precipitates a great quantity of vitrifiable sand.

            But, what clearly demonstrates the existence of sand, and even of flint and glass in clay, is, that the reunion of its parts, by the action of fire, restores it to its original form.  Clay, when heated to the degree of calcinations, is covered with [183] a hard coat of enamel; if its internal parts are not vitrified, they become so extremely hard, as to resist the file; they strike fire with the hammer, and acquire all the properties of flint:  A great degree of heat melts and converts them into real glass.

            Clay and sand, therefore, are substances perfectly analogous, and of the same kind.  If clay can be condensed to flint, and even to glass, why may not sand, by resolution, become clay?  Glass appears to be the true elementary earth, and all mixed bodies are only glass in disguise.  Metals, minerals, salts, &c. are only a vitrifiable earth:  Common stone, and other analogous bodies, testaceous [sic] and crustaceous shells, &c. are the only substances which cannot be vitrified, and which seem to form a distinct class.  The former, by the action of fire, may be converted into a homogeneous, hard, and transparent substance, without any diminution of its weight, and upon which no farther change can be made.  The latter, on the contrary, which consist of more active and volatile principles, calcine [sic] in the fire, lose more than a third of their weight, and resume the form of simple earth, without any other change than the dissolution of their constituent parts.  If these bodies be excepted, which are few in number, and of which the combinations produce few varieties in nature, all other substances, and particularly clay, may be converted into glass, and, consequently, are [184] only glass in a decomposed state.  If the fire quickly vitrifies these substances, glass itself, whether simple, or in the form of sand or flint, naturally, but by a slow and insensible progress, resolves into clay.

            In countries where flint is the predominant stone, the fields are commonly strewed with fragments of it:  And, if the place be uncultivated, and if the flints have remained long exposed to the air, without being moved, their upper surface is always white; but the surface next the ground preserves its natural colour, which is very brown.  When these flints are broken, the whiteness appears to be not superficial only, but penetrates more or less into their internal parts, and forms a belt, which in some is not very deep, but, in others, occupies nearly the whole stone.  This white part is somewhat granulated, perfectly opaque, as tender as free-stone, and adheres to the tongue like the boles.  But the other portion of the flint is smooth and polished, has neither thread nor grain, and preserves its original colour, its transparency, and its hardness.  When this half decomposed flint is put into a furnace, the white part becomes red like a brick, and the brown part becomes exceedingly white.  Why shall we conclude, with a famous naturalist, that flints of this kind are imperfect, and that they are not old enough to have acquired their perfect state?  For why should they be all imperfect? And why should they be uniformly [185] imperfect on the side only that is exposed to the air?  It is, on the contrary, much more probable, that they are changed from their original state, and partly decomposed, and that they are gradually resolving into clay or bole.  If this reasoning should appear to be unsatisfactory, expose to the air the hardest and blackest flint, in less than a year the colour of its surface will be changed; and, if the experiment be farther prosecuted, the flint will be gradually to lose its hardness, its transparency, and its other specific characters, and make daily approaches to the nature of clay.

            Sand undergoes the same changes as flint.  Every grain of sand may, perhaps, be considered as a small flint, and every piece of flint as a collection of fine sand cemented together.  The first example of the decomposition of sand is exhibited in that shining, but opaque powder, called mica, with which clay and slate always impregnated.  The quartz, or perfectly transparent flints, in decomposing, product fat and soft talks [sic], such as those of Venice and Russia, which are as ductile and vitrifiable as clay; and, it appears, that talk [sic] is the mean between glass, or transparent flint, and clay; but that the gross and impure flints, in decomposing, are converted into clay without any intermediate state.

            Our made glass undergoes the same change; when long exposed to the air, it decomposes, and, as it were, corrupts.  At first, it takes on a [186] number of colours, then it exfoliates, and, in handling it, we perceive that many shining particles fall off.  But, when its decomposition is farther advanced, it bruises between the fingers, and is reduced to a very white, talky [sic], and impalpable powder.  Art also imitates nature in the decomposition of glass and flint.  “Est etiam certa methodus, solius aquae communis ope, filices et arenam in liquorem viscosum, eundemque in sal viride convertendi, et hoc in oleum rubicundum, &c.  Solius ignis et aquae ope, speciali experimento, durissimos quosque lapides in mucorem resolvo, qui distillans subtilem spiritum exhibit, et oleum nullis laudibus praedicabile.”*

            These matters shall be more fully considered when we come to treat of metals. We shall here only add, that the different strata of the globe, consist either of materials which may be considered as actual vitrifications, or analogous to glass, and possessing its most essential qualities; and that it is also evident, from the decomposition of glass and of flint, which daily takes place, there results a genuine clay; we may therefore conclude, with a high degree of probability, that sand and clays have originally been the scoriae of burnt matter, especially when we join, to the above circumstances, the proofs a priori which have been employed to show that the earth was formerly in a state of liquefaction occasioned by the operation of fire.  [187]

*  This opinion, that the earth was entirely covered with water, corresponds with the sentiments of several antient philosophers, and likewise with those of many of the fathers of the church.  In mundi primordio, aqua in omnem terram stagnabat, says St John of Damascus, lib. 2. cap. 9. Terra erat invisibilis, quia exundabat aqua et operiebat terram; St Ambrose, lib. I. cap. 8.  Submersa tellus cum effet, faciem ejus inundante aqua, non erat adspectabilis; St Basile, Hom. 2. See likewise St Augustine, lib. 1. cap. 12 [back to page 159].

* See Woodward’s Essay, p. 136 [back to page 168].

*  See Verenii Geograph. gen. p. 46 [back to page 170].

*  See Mem. De l’Acad. ann. 1705, p. 30.

+  Ibid. ann. 1716, p. 14 [back to page 175].

*  See Voyag. De Franc. Pyrard, vol. 1. p. 107 [back to page 177].

*  Vid. Becher. Phys. Subterr [back to page 187].